Internal combustion engine automatic compression ratio varying means



April 11, 1939. YJHlRONAKA 2,153,691

INTERNAL COMBUSTION ENGINE AUTOMATIC COMPRESSION RATIO VARYING MEANS Filed April 13. 1936 Fyi. F92. g a, 16 Q 12 I J6 J3' -22 Z4 2 i5 1- 2a 21 4 f? t 3 5 20' 2' 6 O r 8 7 l1 us, 17

Z.%%Wj@ $4 Patented Apr. 11, E939 STATES INTERNAL COMBUSTION. MATIC COMPRESSION MEANS Enema AUTO- aA'rro mama Yasusaburo Hironaka, Tsuwano-cho, Kanoashi- Japan,v assignor oi one-hall to Kenjiro Tsuneda, Kyoto, Japan Application April 13, 1936, Serial No. 74,210 1 Claim. (].123-48) This invention relates to an internal combus tion-engine .which is provided with a mechanism for automatically and accurately varying the compression ratio responsive to the variation of the vacuum in the air inlet pipe or intake manifold of the engine.

The accompanying drawing illustrates a form oil-embodiment of this invention, in which:

Figure l is a longitudinal section of an internal combustion engine according to this invention;

Figure 2 is a plan in section of the controlling device; and 1 Figure 3 is a detailin section taken angle to Figure 1, showing the piston portion only.

Throughout the, various figures, same reference numerals referpto same parts.

It has been well recognized that the advanced ignition 'or knocking phenomena, which occur crease indirect proportion to the load. Consequently, in

during the operation. of

an internal combustion engine, decrease in inverse proportion to the number of revolutions of the engine and they in-- increase of load. Such variation directly influences the vacuum in the air inlet pipe orintake manifold of the englue, and said vacuum is directly proportional to the engine speed and is inversely proportional to order to automatically regulate the compression ratio, it is theoretically desirable to utilize variations of said suction pressure in the air inlet pipe or intake manifold of the engine for the purpose of securing the most accurate adjustment.

This invention is based upon such principle, and aims to provide means for automatically regulating the compression ratio of an internal combustion engine fold.

Referring now to the accompanying drawing, 11 designates a piston having a piston pin 2. Journaled on said pin 2 is a sleeve 3 which is eccentric to the axis of the pin 2. Said sleeve 3 is formed at its one end with a worm gear l which,

is concentric with the pin 2. At its upper end, piston rod 5 is formed as an eccentric strap surrounding the eccentric sleeve 3. Meshing with the worm gear 4 is a worm shaft 6', of which the lower end is formed as a square shaft 7, and it Said pinion & meshes with a toothed rack bar Ill, one end of which bar carries a piston it in a servo-motor cylinder H. The piston I2 is normally held in the upper position, biased outwardly by means of spring l3. Adjacent an inlet port ll of the at right by utilizing the variation of the l suction pressure in the suction pipe or inlet maniservo-motor cylinder H, a: valve chest I5 is formed, in which is provided a double acting controlling valve 86 adapted to control a supply pipe I? which is connected to the combustion chamber of the engine. In said supply pipe I! is provided a check valve which is adapted to be opened by the explosion gas when its pressure reaches a predetermined value. A discharge pipe I8 is connected near the back seat for the valve l8. At the other end, the valve stem i9 has vacuum piston in a vacuum cylinder 2i, and the piston 20 is normally biased by aweak spring 22 in such direction that the supply port H is held open. The vacuum through conduit 23 with the intake manifold 24 of the engine, so that the piston 2G is normally under the influence of the pressure in said inlet manifold.

As the pressure fluid for the servo-motor above described, explosion gas from the engine cylincylinder 2! is connected ders is preferably employed; If necessary, howfold 25 decreases, so that the pressure in the vacuum cylinder 2i increases progressively toward the atmospheric pressure; Then, the spring 22 becomes eflfective, pushing the piston 21B outwardly, and the valve it opens the inlet port 91, so that the pressure fluid from the port ll enters the servo-motor cylinder it through the port it and actuates the piston l 2, compressing the spring 83. The pinion 8 is rotated by the toothed rack ill forming the piston rod of said piston l2, so that the square shaft 7, worm 6, worm gear 4, cccentric sleeve 3 forming the compression ratio varying mechanism are actuated, whereby the distance between the piston head and the piston pin is shortened. Thus, the compression ratio is progressively decreased. On the other hand, whenthe load decreases and the degree of vacuum in the inlet manifold increases, increasing sirable ata decreased motor cylinder is discharged into atmosphere, and the servo-motor piston i2 returns to the normal position under the influence of the spring ll. Thus the compression ratio is increased by the reverse action of the regulating mechanism.

While in internal combustion engine it is deload to give higher compression ratio compared with that at full load, in view ofthe decrease of suction, it has not been possible to obtain such effect in usual Otto cycle engines in which the combustion chambers are of the fixed volume. This invention aims to provide a mechanism responsive to the suction pressure within the inlet manifold for automatically and accurately varying the compression ratio, for the purpose of always obtaining best compression ratio for various conditions of load, number of revolutions, kind of fuel, and engine temperature, etc. According to this invention, it is possible to obtain increased thermal emciency for various loads, and particularly a' considerably increased thermal efliciency at lighter load.

What I claim is:

An internal combustion engine, comprising 9.

servo-motor mechanism for varying the compression ratio in the engine cylinder, means responsive to and controlled by the explosion gas pressure for actuating said servo-motor, a double acting valve controlling the admission to said servo-motor of the explosion gas coming from the engine on one hand, and controlling the discharge of said explosion gas on the other hand, a vacuum cylinder connected at its one end to the intake pipe oi the engine, and open to the atmosphere at the other end, a vacuum piston in said vacuum cylinder and connected for operating said double acting valve, and a weak spring normally acting upon said vacuum piston against the action of said vacuum, the arrangement being such that the controlling valve is opened to permit the admission of the explosion gas to said servo-motor as the vacuum approachesatmosphehc pressure to decrease the compression, and is'closed to permit discharge of said explosion gas irom said servo-motor in reversed condition to increase the compression in the engine cylinder.

YASUSABURO HIRONAKA. 

